This invention relates generally to golf balls and more specifically, to a multi-layer golf ball and a composition therefore. In particular, this invention relates to a golf ball having a core, a cove and at least one intermediate layer disposed between the core and cover, wherein the intermediate layer is formed from a blend comprising at least one glycidyl polymer. The multi-layer golf bails of the present invention have been found to provide good distance, durability, and desirable playing characteristics.
Conventional golf balls can be divided into two general types or groups: solid balls or wound balls. The difference in play characteristics resulting from these different types of constructions can be quite significant.
Balls having a solid construction are generally most popular with the average recreational golfer because they provide a very durable ball while also providing maximum distance. Solid balls are made with a solid core, usually formed of a crosslinked rubber, which is encased by a cover material. Typically the solid core is formed of polybutadiene which is chemically crosslinked with zinc diacrylate and/or similar crosslinking agents and is covered by a tough, cut-proof blended cover. The cover is generally formed of a material such as SURLYN, which is a trademark for an ionomer resin produced by DuPont of Wilmington, Del. The combination of the core and cover materials provide a ball that is virtually indestructible by golfers. Further, such a combination imparts a high initial velocity to the ball which results in improved distance. Because the materials of which the ball is formed are very rigid, solid balls generally have a hard xe2x80x9cfeelxe2x80x9d when struck with a club. Likewise, due to their hardness, these balls have a relatively low spin rate which provides greater distance.
At the present time, the wound ball remains the preferred ball of more advanced players due to its spin and feel characteristics. Wound balls typically have either a solid rubber or liquid center core around which many yards of a stretched elastic thread or yarn are wound. The wound core is then covered with a durable cover material such as a SURLYN or similar material or a softer cover such as balata or polyurethane. Wound balls are generally softer and provide more spin than non-wound balls, which enables a skilled golfer to have more control over the ball""s flight and final position. Particularly, with approach shots into the green, the high spin rate of soft, wound balls enables the golfer to stop the ball very near its landing position.
A number of patents have been issued that are directed towards modifying the properties of a conventional solid ball by altering the typical single layer core and single cover layer construction to provide a multi-layer ball having such as a dual cover layer, dual core layer and/or a ball having a mantle layer disposed between the cover and the core. The inventions disclosed in the prior art patents are directed towards improving a variety of golf balls physical properties that help determine xe2x80x9cin-playxe2x80x9d characteristics.
Several patents are directed towards improving the carry distance of such balls. For example, U.S. Pat. No. 4,863,167 relates to a three piece solid golf ball having increased flight distance, wherein the ball has a center portion and an outer layer formed from a rubber composition, wherein the outer layer is harder than the center portion and further contains a gravity-adjusting filler so as to impart a higher specific gravity to the outer layer than that of the center portion. U.S. Pat. No. 5,184,828 relates to a solid three-piece golf ball having improved rebound characteristics and carry distance while maintaining an adequate spin rate, wherein these characteristics are allegedly obtained by controlling the size of the polybutadiene inner core and outer layer as well as their specific gravity and hardness. According to the ""828 patent, the key to obtaining the desired rebound characteristics is that the maximum hardness (42-62 Shore D) must be located at the interface between the core and the mantle and the hardness must then decrease both inwardly and outwardly. U.S. Pat. No. 4,714,253 is also directed towards a three-piece golf ball having an improved rebound coefficient. This golf ball has a core with a Shore C hardness of 57-80 in its center, but not more than 83 at a distance between 5-10 mm from its center and an outer layer with a Shore C hardness of 70-83.
Additionally, there are a number of patents directed towards improving the spin and feel of solid balls while maintaining the distance provided by the solid construction. For example, U.S. Pat. No. 5,072,944 discloses a three-piece solid golf ball having a center layer and an outer layer that are prepared from a rubber composition, wherein it is desirable that the center core layer is softer than the outer layer, the layers having a hardness (Shore C) of 25-50 and 70-90, respectively.
U.S. Pat. No. 4,625,964 relates to a solid golf ball having a polybutadiene rubber core of a diameter not more than 32 mm, a polybutadiene rubber intermediate layer having a specific gravity of lower than that of the core material, and a cover. U.S. Pat. No. 4,650,193 is directed towards a solid golf ball having a core comprising a central portion and an integral outer layer, wherein the core is a curable elastomer such as polybutadiene which is treated with a cure altering agent to soften an outer layer of the core, to produce a central layer with a hardness (Shore C) of greater than 75 and an outer layer with a hardness (Shore A) of less than 80.
U.S. Pat. No. 4,848,770 discloses a solid three-piece golf ball which includes a core of a highly filled synthetic rubber or polymeric material, an intermediate mantle of an unfilled synthetic rubber and a cover. The core and intermediate mantle have a hardness of between 50-95 Shore D. U.S. Pat. No. 5,002,281 is directed towards a three-piece solid golf ball which has an inner core having a hardness of 25-70 (Shore C), an outer shell having a hardness of 80-95 (Shore C) and a cover. Further, the specific gravity of the inner core must be greater than 1.0, but less than or equal to that of the outer shell, which must be less than 1.3.
The prior art discloses a variety of materials other than polybutadiene for use as intermediate layers. For example, U.S. Pat. No. 5,253,871 concerns a golf ball having a three-piece structure comprising an elastomer core, an intermediate layer of a thermoplastic material containing at least 10% of ether block copolymer, preferably blended with an ionomer, and a thermoplastic cover. U.S. Pat. No. 5,681,898 is directed to a multilayer golf ball having a conventional polybutadiene core, an ionomer cover and an intermediate layer formed from a blend of an ethylene methacrylic acid copolymer and a vulcanizate formed from polybutadiene and a peroxide curing agent. U.S. Pat. Nos. 5,439,227 and 5,556,098 both disclose multilayer golf balls which have a conventional polybutadiene core, conventional covers and an intermediate layer formed from a polyetherester block copolymer blended with an ionomer.
Further, there are also several patents which are directed to golf balls having multiple cover layers. For example U.S. Pat. No. 4,431,193 relates to a golf ball having a multilayer cover wherein the inner layer is a hard, high flexural modulus ionomer resin and the outer layer is a soft, low flexural modulus ionomer resin, and wherein either or both layers may comprise a foamed ionomer resin. U.S. Pat. No. 5,314,187 also relates to golf balls having a multiple layer cover, wherein the outer layer is molded over the inner layer and comprises a blend of balata and an elastomer and the inner layer is an ionomer resin. U.S. Pat. No. 4,919,434 is directed towards a golf ball having a cover which comprises an inner layer and an outer layer, each of which comprise a thermoplastic resin. Preferably the layers are comprised of materials that are capable of bonding with each other, for example, by heat, or by other means which are readily known to one of ordinary skill in the art.
Additionally, U.S. Pat. No. 5,631,324 is directed to a golf ball wherein the terpolymer composition of the core, mantle layers, or cover comprises an epoxy (i.e., glycidyl moiety) and an ionomer material. U.S. Pat. No. 5,155,157 provides compositions useful in the manufacture of one-, two- and three-piece golf balls that comprises blends of block copolymers, an ionomer material, and an epoxy-containing compound. U.S. Pat. No. 5,565,524 provides a golf ball having a cover that comprises an ionomer material and a glycidyl-group-containing olefinic copolymer. U.S. Pat. No. 5,543,467 discloses a golf ball having a core and a cover in which the base material of the cover comprises a maleic anhydride-modified olefinic copolymer, an ionomer resin, and a glycidyl-group-containing olefinic copolymer.
However, none of the patents discussed above disclose the multi-layer ball of the current invention that employs the materials, and has the improved golf ball properties, as disclosed herein.
The present invention is directed towards an improved multi-layer golf ball which includes a core having a compression of no greater than about 90, a cover layer having a Shore D hardness of about 54 to 72, and at least one intermediate layer disposed between the cover and the core, wherein the at least one intermediate layer is formed from a blend including a glycidyl polymer and the golf ball has a coefficient of restitution of greater than about 0.76.
In one embodiment, the blend further includes a second component, wherein the second component is a thermoplastic material. In another embodiment, the second component is selected from the group consisting of polyesterester block copolymers, polyetherester block copolymers, polyetheramide block copolymers, dynamically vulcanized thermoplastic elastomers, styrene-butadiene elastomers, thermoplastic polyurethanes, thermoplastic polyesters, polymers formed using a metallocene catalyst, and blends thereof. Preferably, the second component includes a polyetherester block copolymer. In another embodiment, the blend further includes a filler in an amount sufficient to provide the at least one intermediate layer with a specific gravity of greater than about 1.2. In still another embodiment, the intermediate layer has a specific gravity of greater than about 1.25. In yet another embodiment, the filler includes zinc oxide.
In another embodiment, the blend includes about 10 to about 50 percent by weight glycidyl polymer, about 25 to 75 percent by weight second thermoplastic component and about 5 to about 40 percent by weight filler. Preferably, the blend includes about 15 to 30 percent by weight glycidyl polymer, about 40 to 70 percent by weight second thermoplastic component and about 15 to 30 percent by weight filler. In another embodiment, the intermediate layer has a Shore D hardness of about 35 to 50 and a flexural modulus of about 1,000 psi to 8,000 psi. In another embodiment, the golf ball has a compression of no greater than about 90. In still another embodiment, the cover includes at least one of a thermoplastic or a thermoset material.
The present invention is also directed to a golf ball having a core including polybutadiene, a cover layer having a Shore D hardness of about 54 to 72, and at least one intermediate layer disposed between the cover and the core, wherein the at least one intermediate layer is formed from a blend including about 15 to 30 weight percent of a glycidyl polymer, about 15 to 30 weight percent zinc oxide, up to about 70 weight percent polyetherester block copolymer; and wherein the golf ball has a coefficient of restitution of greater than about 0.78.
In one embodiment, the core blend further includes calcium oxide. Additionally, the intermediate layer is formed from a blend including about 19 to 21 weight percent glycidyl polymer, about 20 to 22 weight percent zinc oxide, and about 58 to 60 weight percent polyetherester block copolymer. In another embodiment, the intermediate layer has a Shore D hardness of less than about 40 and a flexural modulus of less than about 10,000 psi. In still another embodiment, the blend includes at least about 40 weight percent polyetherester block copolymer.
The present invention is also directed to a golf ball having a coefficient of restitution of greater than about 0.7 and a compression of at least about 50, wherein the ball includes a core and a cover having at least one layer disposed concentrically about the core, wherein the layer is a composition including a glycidyl polymer composition and a thermoplastic, selected from the group of copolyesters, polyamides, polyetherester block copolymers, polyesterester block copolymers, polyetheramide block copolymers, polyesteramide block copolymers, and polyurethane, wherein the material has a flexural modulus less than 20,000 psi.
In one embodiment, the material includes a filler sufficient to produce a specific gravity of greater than about 1.2. In another embodiment, the glycidyl polymer composition comprises at least one repeat unit of formula 1: 
wherein R1 is hydrogen, linear or branched alkyl group having the formula CxH2x+1, aromatic, or alicyclic, where x is an integer from 1 to about 8; R2 is hydrogen, linear or branched alkyl group having the formula CyH2y+1, aromatic, or alicyclic, where y is an integer from 1 to about 20; and n is an integer ranging from 1 to about 6.
In another embodiment, the glycidyl polymer composition includes a repeat unit of formula 2: 
wherein R3, R4, and R5 are hydrogen, linear or branched alkyl group having the formula CxH2x+1, aromatic, or alicyclic, where x is an integer from 1 to about 8; R6 is hydrogen, linear or branched alkyl group having the formula CyH2y+1, aromatic, or alicyclic, where y is an integer from 1 to about 20; o ranges from about 1 to about 99 weight percent of the total glycidyl polymer; p ranges from about 99 to about 1 weight percent of the total glycidyl polymer; and q is an integer ranging from 1 to about 6.
In still another embodiment, the glycidyl polymer composition includes a repeat unit of formula 3: 
wherein R7, R8, R9, and R11 are hydrogen, linear or branched alkyl group having the formula CxH2x+1, aromatic, or alicyclic, where x is an integer from 1 to about 8; R10 and R12 are hydrogen, linear or branched alkyl group having the formula CyH2y+1, aromatic, or alicyclic, where y is an integer from 1 to about 20; r ranges from about 1 to about 99 weight percent of the total glycidyl polymer; s ranges from about 1 to about 50 weight percent of the total glycidyl polymer; t ranges from about 1 to about 30 weight percent of the total glycidyl polymer; and u is an integer ranging from about 1 to about 6.
In one embodiment, the cover includes an outer layer and an inner layer and the composition forms the inner layer. In another embodiment, the inner layer has a first hardness and the outer layer has a second hardness greater than the first hardness. In still another embodiment, the core has a third hardness within 10 Shore D of the first hardness and less than the second hardness.
In another embodiment, the inner layer has a specific gravity greater than about 1.2 In another embodiment, the inner layer has a flexural modulus of less than about 10,000 psi.